The present invention relates to a coating composition and more particularly to a solution of a hydrolyzed or partially hydrolyzed alkoxysilane, and an arylcyclobutene resin, and to a solventless process for preparing hydrolyzed or partially hydrolyzed alkoxysilanes.
It is known to use hydrolyzed alkoxysilanes as adhesion promoters or coupling agents for various polymeric materials. The hydrolyzed alkoxysilanes are typically used as a primer layer, i.e., they are applied to the substrate first, followed by application of the polymeric material. The alkoxysilanes are typically hydrolyzed to form aqueous and/or protic solutions before being applied as thin films. However, most organoalkoxy-silanes are not soluble in water and must be dissolved first in a compatible organic solvent, such as an alcohol. Unfortunately, upon application of the aqueous alkoxysilane/alcohol mixture, a discontinuous film forms which contains voids where the film has not covered the substrate.
It is also known that a hydrolyzed alkoxysilane can be used as an adhesion promoter primer layer for arylcyclobutene resins. For example, in Proc. MRS, Vol. 323, pg. 365, 1994, Adhesion of Cyclotene.TM. (BCB) Coatings on Silicon Substrates, a prehydrolyzed solution of 3-methacryl-oxypropyltrimethoxysilane (MOPS) in methanol was used as an adhesion promoter for Cyclotene.TM.. However, the MOPS solution is extremely difficult to deposit uniformly, forming agglomerates on the surface, which leads to reliability problems when used in fabricated parts.
It is also known to hydrolyze specific silanes in the absence of a solvent. U.S. Pat. No. 3,350,345 to Vanderbilt et al. describes a process of hydrolyzing specific silanes by adding water to hydrolyze at least one but not all of the alkoxy groups. The specific silanes have reactive groups such as amino, mercapto, carboxyl or cyano, which self-catalyze the hydrolysis process.
Accordingly, it remains highly desirable to provide coating compositions containing an arylcylcobutene which does not exhibit the foregoing disadvantages as well as to provide a process which does not use an organic solvent for hydrolyzing alkoxysilanes.